My work involves two projects. One of these projects concerns itself with the developmental interactions which take place between different tissues during asexual reproduction as Ascidians. This problem has been approached by studying the effects of a mutation which blocks the process of asexual reproduction by vascular budding at an early stage in the ascidian Botrylloides diagense. Our results show that this mutation effects the blood cells of these animals; this has been established by studying the effects of making cellular interchanges between normal and mutant individuals on the ability of the composite individuals that result to reproduce asexually. Histological studies of these mutant animals are now underway. The other project concerns itself with identifying the mechanisms that bring about the segregation of developmental potential during the first stages of the development of the Ctenophore egg. The first differential division which occurs during the development of these eggs takes place during the formation of the eight cell stage; each of the four cell stage blastomeres produces one daughter cell with the potential to form comb plate cilia and one daughter cell with the potential to produce light. Experiments that we have done in which different amounts of cytoplasm were removed from defined regions of the blastomeres at the 2 and 4 cell stages have shown that these localizations have their origin at the 4 cell stage.